Beans, such as green beans, as harvested have a central edible pod with blossom and stem ends which are fibrous and non-tender. These ends have a low palatablility and are shunned by the consumers of the beans. Therefore, prior to canning and marketing beans it is essential to remove as many of the stem and blossom ends as possible.
Specialized machines known as bean snippers have long been used to remove the ends from a flow of beans prior to canning or packaging. A conventional bean snipper has a rotatable drum formed from a number of cylindrical shell sections with slots extending circumferentially. The slots are adapted to allow the ends of beans to protrude as they tumble in the rotating drum. Knives sliding on the rotating exterior of the cylindrical sections cut off the protruding undesirable blossom and stem ends. Axially spaced partitions within the drum are adapted to maximize the likelihood that pods being processed in the drum will enter the slots so that the bean ends will protrude through the slots for snipping. A passageway in each partition allows the beans to migrate down the length of the rotating drum when the drum is elevated at one end.
Invariably stalks, leaves, malformed beans, and other unpalatable or otherwise undesirable trash is harvested along with the beans. To present the bean consumer with pure beans uncontaminated by such trash, it is desirable to separate the stalks and other thin material from the beans within the bean snipper apparatus.
The molded plastic cylindrical shell sections or pockets which form the walls of the snipper drum are generally of two types: those with straight slots, and those with wavy slots. The straight slot pockets advantageously allow a thicker stalk to exit the drum for a given slot width. However, straight slots do not restrain the bean ends inserted therein and allow the beans to slide in the process of being snipped. This sliding results in an unappealing and undesirable ragged end cut.
The wavy slot pockets clasp the bean ends more securely than the straight slot pockets, but because of the slot geometry, restrict the escape of trash and are liable to blockage.
The positioning of a bean with proper orientation in a slot for effective snipping is achieved by a random process. The snipper drum is rotated to provide an even shower of beans into the drum slots below. A bean may fall so that it is parallel with a slot, at an angle within the plane of a slot, or generally perpendicular to the slot, with its end protruding outside the drum. Only the last possibility will result in satisfactory snipping of a bean end.
In the random travel of the thousands of beans from the entrance to the exit of the snipper drum, it is desired that each bean twice fall into a slot in proper orientation, once to snip the blossom end and once to snip the stem end. Modifications of the interior drum geometry have been attempted to increase the probability of a bean reaching a slot in the proper orientation. Screens above the slots and baffles on either side of the slots have been employed, although still having bean snipping performance that is not fully satisfactory. Planar baffles axially spaced along the length of the drum have been found effective in reducing the percentage of beans which fall into the pockets and lie across the slots.
Although conventional bean snippers are effective in snipping well over 90 percent of the bean ends, even a few percent of unsnipped beans are undesirable and appreciably reduce the quality of the processed beans.
What is needed is an apparatus which effectively snips ends of a high percentage of beans introduced therein.